The french word for the cross in typography is "obèle" ; obélisque exists too, but is apparently a bit old-fashionned.
Maybe Goscinny was indeed accustomed to the version more widely used in English. 
See : 
http://www.apropos-savoir.fr/_pg/search ... ob%C3%A8le
In reply to Invisifan, here are translations of typographical signs in french, in the form that hardly anybody uses :
  ampersand "&",  = "perluète" or "esperluette" in french 
  octothorpe "#" = "octothorpe", "croisillon" 
                     "<at>" = 'arrobe' or 'arobase' (from the Arabic ar-robas, meaning... one quarter !). 
  Look like comics swear-words, all these #<at>& !!     ;D